The plug magazine and the firing handle extend substantially perpendicular to the axis of the casing and are offset with respect to each other along this axis, the magazine communicating with the plug guide, and the handle being connected to the casing. The battery housing generally extends substantially perpendicular to the axis of the casing, along the plug magazine.
In certain devices the cartridge housing extends parallel to the axis of the casing, between the casing and the handle, whereas in other devices the fuel cartridge is housed inside the firing handle.
These fixing devices are generally poorly balanced so that an operator, when holding the device by gripping the firing handle with one hand, experiences difficulties in handling the device and stabilising it in the firing position.